Getting the Timing Right – Ovulation and Why the Luteal phase is so important

When trying to conceive, it is so important to know when ovulation occurs and to ensure the Luteal Phase (the phase after ovulation) is long enough to sustain a pregnancy.  The majority of clients I see in my clinic will always tell me they know exactly when they are ovulating and will always have intercourse around that time. However, most are shocked when they start tracking their cycle (using the Basal Body Temperature (BBT) method), that they are ovulating either later or earlier than first thought; they are completely missing their fertile window! It is quite a revelation and that typical ‘penny drop’ moment, but in a positive way. ‘Oh, no wonder I haven’t conceived yet! I’m not having sex at the right time’.

Ask most doctors and they will tell you everyone has a 28 day cycle with ovulation occurring around Day 14. This is the optimum situation as it gives you the most opportunities over the course of the year to conceive. However this does not occur in a large percentage of women, and understanding your cycle and pin pointing ovulation is fundamental in increasing your chances of a successful conception.


Ovulation normally occurs around Day 14 of an optimum 28 day cycle. However, this can vary greatly from woman to woman. Me, personally, I had a 40 day cycle whereby ovulation did not occur until Day 26!

Let’s take a look at the science behind this pinnacle phase.

As oestrogen peaks throughout the Follicular Phase it triggers a spike in Luteinising Hormone, or LH.  Ovulation occurs as this increase in LH causes the dominant follicle to rupture and release an egg (ova) and the Corpus Luteum (which has been formed from the follicle), produces the hormone Progesterone which sustains a pregnancy, up until 12 weeks, when the placenta takes over. Remember, the last four days of the Follicular Phase, plus ovulation day, are your fertile window. This is when you are most likely to become pregnant if you have intercourse without using any form of birth control. This is because sperm can live in a woman’s body for around four to five days if conditions are favourable.

The most accurate way to confirm ovulation has definitely occurred (other than having a blood test) is by tracking your cycle through the BBT method. This method gives no warning of imminent ovulation but confirms it has occurred through the sharp rise (biphasic temperature shift) of temperature after ovulation. It’s the hormone progesterone which is dominant in the Luteal Phase and has the effect of increasing the basal body temperature. Three consecutive high temperatures that are 0.2 degrees Celsius above the previous six lower temperatures confirm ovulation, and therefore this pinpoints exactly when ovulation occurred. If your cycles are regular, over the course of a couple of months of recording your BBT, you will be able to tell when your most fertile period is.

Many women seem to worry about whether or not they are ovulating and therefore use

Ovulation Prediction Tests or OPT’s.  OPT’s have become quite popular over the last few decades and can be quite useful in determining your fertile period.  However, OPTs work by measuring the presence of Luteinizing Hormone (LH) in the urine. LH surges anywhere between 12 and 48 hours before ovulation, therefore they only predict a short fertile window; i.e. the day/days before you ovulate.  It is recommended that they are used along with temperature tracking. I also find some clients will start worrying unnecessarily if the OPT shows no surge at all. Not detecting a LH surge may not mean you have not ovulated that particular month, it maybe simply because your cycle is out of synch.  Another air of caution if you do use OPT’s – they are not suitable if you have Polycystic Ovary Syndrome (PCOS) as these women have naturally higher levels of LH in their urine therefore the OPT may give several false positive readings.

If you do choose to use OPT’s, I would recommend the following:

  • Test every day starting on the day you expect to be most fertile, for example, if you usually ovulate around Day 14 test from Day 10 onwards.
  • If you are unsure when you ovulate then start taking the tests when you start observing fertile (stretchy, egg white consistency) cervical mucus.
  • If you get a positive result there is no need to test again. First morning urine is usually not the best for OPTs since your LH surge usually begins in early morning when you are still sleeping and may not be apparent in your first morning urine. Therefore late morning or early afternoon is usually best.
  • Test around the same time every day.
  • Record your OPT results as positive if the test line is as dark as or darker than the control line. Record your results as negative if the test line is lighter than the control line.

Luteal Phase

The Luteal Phase is the phase after ovulation. It is dominated by the hormone Progesterone which makes the womb lining thick and spongy in preparation for receiving a fertilized egg, and provides the support to maintain a pregnancy.

Progesterone has the following physical effects on your body:

  • Increases the BBT which confirms ovulation.
  • Makes the cervix hard and dry.
  • Makes the cervix secrete ‘mesh mucus’ which is thick, acidic and impenetrable.
  • Makes the cervix position closed and low.

The Luteal Phase usually lasts between 12 and 16 days long. It is very important that the phase is at least 12 days long – if not, a pregnancy cannot be sustained. A Luteal Phase shorter than 10 days is classed as a ‘Luteal Phase Defect’ and is due to a progesterone deficiency. This defect can only be determined if you track your cycle using the BBT method.  This is the scenario if you have a Luteal Phase of 8 days: the egg is released and travels down the fallopian tube. Before it has a chance to implant into the uterine wall, the endometrium has already started to shed in preparation for the next menstrual bleed. Therefore even if fertilisation had occurred, a pregnancy would not occur due to failure to implant.

Progesterone deficiency is quite common, particularly with the increase use of the oral contraceptive pill, and may not be something to be concerned about. It may however indicate a deficiency in other important fertility hormones. Dietary changes and the right supplementation through a nutritionist will rectify most progesterone deficiencies.

If you would like to learn more about tracking your cycle and undertake a thorough Fertility Consultation that looks at diet, lifestyle, nutrition and fertility tests, then please take a look here.

We are currently offering free 30 minute consultation to discuss your individual case and to see how we may be able to help you. Also available over the telephone and Skype.

By Katy Flello of Natural Fertility Clinic Ltd